JPH0729158A - Magnetic recording medium - Google Patents

Magnetic recording medium

Info

Publication number
JPH0729158A
JPH0729158A JP17440593A JP17440593A JPH0729158A JP H0729158 A JPH0729158 A JP H0729158A JP 17440593 A JP17440593 A JP 17440593A JP 17440593 A JP17440593 A JP 17440593A JP H0729158 A JPH0729158 A JP H0729158A
Authority
JP
Japan
Prior art keywords
magnetic
layer
magnetic layer
iron
coercive force
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP17440593A
Other languages
Japanese (ja)
Inventor
Akira Ishikawa
彰 石川
Shunji Tako
俊二 田高
Hideyuki Kobayashi
秀行 小林
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kao Corp
Original Assignee
Kao Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kao Corp filed Critical Kao Corp
Priority to JP17440593A priority Critical patent/JPH0729158A/en
Publication of JPH0729158A publication Critical patent/JPH0729158A/en
Pending legal-status Critical Current

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  • Paints Or Removers (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

PURPOSE:To improve an S/N and a travelling performance, eliminate the filling of the, avoid the degradation of a saturated flux density during a storage period, etc., by a method wherein the respective materials of a first magnetic layer and a second magnetic layer which are formed on a substrate are specified. CONSTITUTION:A magnetic layer formed on a substrate has a double-layer structure composed of an upper layer and a lower layer. The lower first layer is made of metal powder. Iron powder whose main component is iron or powder of alloy such as iron/cobalt, iron/nickel, etc., is used as the metal powder. The average long axis particle diameter and the axis ratio of the metal powder are not specifically limited. The coercive force of the metal powder is selected to be 500-1300Oe and smaller than the coercive force of the material of the upper second magnetic layer. The upper second magnetic layer is made of cobalt-coated iron oxide whose coercive force is not smaller than 1300Oe, preferably 1300-2000Oe, whose average particle diameter is not limited but average long axis length is 0.01-0.1mum and short axis length is 0.01-0.1mum and which has a needle-shape. If the coercive force of the second layer material is smaller than 1300Oe, a high output can not be obtained.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は磁性層を2層構造とした
磁気記録媒体に関し、更に詳しくは電磁変換特性、耐久
性に優れた磁気記録媒体に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a two-layer magnetic layer structure, and more particularly to a magnetic recording medium excellent in electromagnetic conversion characteristics and durability.

【0002】[0002]

【従来の技術】塗布型の磁気記録媒体は、磁性粉末を結
合剤と有機溶剤に分散してなる磁性塗料をポリエステル
等の基材上に塗布、乾燥して得られるものであるが、今
日、高画質ビデオテープ、大容量フロッピーディスク等
の更なる高密度記録に対する要求が高まっている。
2. Description of the Related Art A coating type magnetic recording medium is obtained by coating a magnetic coating material obtained by dispersing magnetic powder in a binder and an organic solvent on a substrate such as polyester and drying it. There is an increasing demand for higher density recording such as high quality video tapes and large capacity floppy disks.

【0003】この目的を達成する磁性粉末としては、鉄
を主体とする強磁性金属粉末が最も多く用いられてい
る。鉄を主体とする強磁性金属粉末は飽和磁化、保磁力
が高く、出力特性に優れる。しかし、化学的に不安定で
錆びやすい(酸化しやすい)ため、酸化により飽和磁化
が低下し、また、ノイズ特性も必ずしも充分でなく、一
般に酸化物系磁性粉末と比べノイズレベルが高い。ま
た、鉄を主体とする強磁性金属粉末はコストが高く実用
面ではいくつかの欠点がある。
Ferromagnetic metal powders composed mainly of iron are most often used as magnetic powders for achieving this purpose. Ferromagnetic metal powder composed mainly of iron has high saturation magnetization and coercive force, and has excellent output characteristics. However, since it is chemically unstable and easily rusts (is easily oxidized), the saturation magnetization is lowered by oxidation, and the noise characteristic is not always sufficient, and generally the noise level is higher than that of the oxide magnetic powder. Further, the ferromagnetic metal powder mainly composed of iron has a high cost and has some drawbacks in practical use.

【0004】また、高密度記録を実現するための方式と
して、垂直磁気記録方式が提案されており、特にこの方
式に適した磁性粉末として六角板状のバリウムフェライ
トが使用されている。しかしながら、バリウムフェライ
トは飽和磁化が低いため、磁気テープや磁気ディスクと
した場合、残留磁束密度が低くなり、低域での出力が不
足する。更に、バリウムフェライトを用いた場合、形成
された磁性層の表面粗さが大きくなるという問題があ
る。
A perpendicular magnetic recording method has been proposed as a method for realizing high-density recording, and hexagonal plate-shaped barium ferrite is used as a magnetic powder particularly suitable for this method. However, since barium ferrite has a low saturation magnetization, when used as a magnetic tape or a magnetic disk, the residual magnetic flux density becomes low and the output in the low range becomes insufficient. Further, when barium ferrite is used, there is a problem that the surface roughness of the formed magnetic layer becomes large.

【0005】このような問題点を解消するために、従来
主流であった単層構造の磁性層を、2層構造にして出力
特性を向上させることが試みられている。例えば、特開
昭62−78718号には、金属磁性粉末(鉄、コバル
ト、ニッケル等又はこれらの合金)を下層に用い、下層
の金属磁性粉末の保磁力と同等以上の保磁力を有する酸
化物磁性粉末(γ−Fe2O3 、Fe3O4 等)を上層に用いて
磁性層が2層構造を有する磁気記録媒体が開示されてい
る。しかしながら、該公報記載の磁気記録媒体は高周波
領域での出力が不充分であり、またS/Nが低いためノ
イズ特性も不充分である。
In order to solve such a problem, it has been attempted to improve the output characteristics by making the magnetic layer having a single-layer structure, which has been a mainstream in the past, into a two-layer structure. For example, in JP-A-62-78718, an oxide having a coercive force equal to or higher than the coercive force of the metal magnetic powder in the lower layer is used by using a metal magnetic powder (iron, cobalt, nickel, etc. or an alloy thereof) in the lower layer. A magnetic recording medium has been disclosed in which magnetic powder (γ-Fe 2 O 3 , Fe 3 O 4, etc.) is used as an upper layer and the magnetic layer has a two-layer structure. However, the magnetic recording medium described in this publication has an insufficient output in a high frequency region, and its S / N is low, so that the noise characteristic is also insufficient.

【0006】この他にも、2層構造の磁性層を有する磁
気記録媒体として、特公平63−56608号、特公平
3−6575号、特公平3−53689、特公平3−5
3690号等があるが、これらは磁気特性又は耐食性の
何れかの改良を目的とするものであり、双方を共に向上
させることは達成されていない。
In addition to this, as a magnetic recording medium having a magnetic layer having a two-layer structure, Japanese Patent Publication Nos. 63-56608, 3-6575, 3-53689, and 3-5.
No. 3690, etc., but these are intended to improve either the magnetic characteristics or the corrosion resistance, and it has not been achieved to improve both of them.

【0007】[0007]

【発明が解決しようとする課題】このように、今後更に
高密度記録化を進めるためには、磁気特性と、走行性等
の物理的特性の両方をバランス良く向上させることが要
求されるが、これらの点については未だ充分ではない。
従って、本発明が解決しようとする課題は、高密度記録
を可能とする磁気記録媒体において、更にS/Nを向上
すること、摩擦係数を下げて走行性を改良すること、ま
たそれによるヘッド目詰まりを解消すること、鉄を主体
とする強磁性金属粉末よりも保存時の飽和磁束密度の低
下を少くなくすることである。
As described above, in order to further increase the recording density in the future, it is required to improve both magnetic characteristics and physical characteristics such as running property in a well-balanced manner. These points are not yet sufficient.
Therefore, the problem to be solved by the present invention is to further improve the S / N in a magnetic recording medium which enables high density recording, to lower the friction coefficient to improve the running property, and to improve the head performance. The aim is to eliminate clogging and to reduce the decrease in the saturation magnetic flux density during storage more than the ferromagnetic metal powder mainly composed of iron.

【0008】[0008]

【課題を解決するための手段】本発明は上記課題を解決
すべく鋭意研究した結果、磁性層を上下2層構造とし、
鉄を主体とする強磁性金属粉末を下層の磁性層に用い、
保磁力が1300Oe以上のコバルト被着酸化鉄を上層
の磁性層に用いることにより、各特性に優れた磁気記録
媒体が得られることを見出し、本発明を完成するに至っ
た。
As a result of intensive studies to solve the above-mentioned problems, the present invention has a magnetic layer having a two-layer structure of upper and lower layers.
Using a ferromagnetic metal powder mainly composed of iron in the lower magnetic layer,
The inventors have found that a magnetic recording medium having excellent characteristics can be obtained by using cobalt-coated iron oxide having a coercive force of 1300 Oe or more in the upper magnetic layer, and completed the present invention.

【0009】すなわち本発明は、基材と、該基材上に形
成され、鉄を主体とする強磁性金属粉末(以下メタル粉
末と略記する)と結合剤とからなる第1磁性層と、該第
1磁性層上に形成され、保磁力が1300Oe以上のコ
バルト被着酸化鉄と結合剤とからなる第2磁性層とを有
する磁気記録媒体を提供するものである。
That is, the present invention comprises a base material, a first magnetic layer formed on the base material, which comprises a ferromagnetic metal powder mainly composed of iron (hereinafter abbreviated as metal powder) and a binder, The present invention provides a magnetic recording medium having a second magnetic layer formed on a first magnetic layer and having a coercive force of 1300 Oe or more and cobalt-coated iron oxide and a binder.

【0010】本発明の磁気記録媒体の第1磁性層に用い
られるメタル粉末は、従来公知の鉄を主体とするものが
使用でき、鉄粉末、或いは鉄とコバルト、ニッケル等の
合金粉末、更にこれらにアルミニウム、クロム、マンガ
ン、珪素、亜鉛、希土類金属元素、遷移金属元素等を含
む合金粉末が挙げられる。メタル粉末の平均長軸粒子
径、軸比は特に限定されず、また、メタル粉末の保磁力
は500〜1300Oeが好ましく、2磁性層のコバル
ト被着酸化鉄の保磁力>メタル粉末の保磁力であるのが
好ましい。第1磁性層は、メタル粉末と結合剤を主成分
とする磁性塗料を基材上に塗布して形成されるが、第1
磁性層の厚さは0.3〜5μm 、好ましくは1〜4μm
である。
The metal powder used in the first magnetic layer of the magnetic recording medium of the present invention may be a conventionally known one mainly composed of iron, such as iron powder or alloy powder of iron and cobalt, nickel, etc. Examples thereof include alloy powders containing aluminum, chromium, manganese, silicon, zinc, rare earth metal elements, transition metal elements, and the like. The average major axis particle diameter and axial ratio of the metal powder are not particularly limited, and the coercive force of the metal powder is preferably 500 to 1300 Oe, and the coercive force of the cobalt-coated iron oxide of the two magnetic layers> the coercive force of the metal powder. Preferably. The first magnetic layer is formed by applying a magnetic coating material containing metal powder and a binder as a main component on a base material.
The thickness of the magnetic layer is 0.3-5 μm, preferably 1-4 μm
Is.

【0011】本発明の磁気記録媒体の第2磁性層には保
磁力が1300Oe以上、好ましくは1300〜200
0Oeのコバルト被着酸化鉄が用いられる。コバルト被
着酸化鉄の保磁力が1300Oe未満であると、高出力
化が達成されない。具体的にはコバルト被着酸化鉄とし
て、Co被着Fe3O4、Co被着Fe2O3、Co被着FeOx(1.34
≦x<1.50)が使用され、特にCo被着FeOxが好まし
い。なお、コバルトドープ型の酸化鉄は保存安定性が悪
いため、好ましくない。
The second magnetic layer of the magnetic recording medium of the present invention has a coercive force of 1300 Oe or more, preferably 1300 to 200.
0 Oe cobalt-deposited iron oxide is used. If the coercive force of the cobalt-deposited iron oxide is less than 1300 Oe, high output cannot be achieved. Specifically, as cobalt-deposited iron oxide, Co-deposited Fe 3 O 4 , Co-deposited Fe 2 O 3 , Co-deposited FeO x (1.34
≦ x <1.50) is used, with Co-deposited FeO x being particularly preferred. Cobalt-doped iron oxide is not preferable because it has poor storage stability.

【0012】また、本発明の磁気記録媒体の第2磁性層
に用いられるコバルト被着酸化鉄は、針状の酸化鉄を核
として、通常のコバルト被着の方法で製造される。磁気
特性はコバルトの添加量、Fe2+量を製造条件等で操作す
ることにより所定のものに調節できる。コバルトの添加
量は通常1〜20重量%(原料の酸化鉄に対して)、好
ましくは2〜15重量%であり、Fe2+の量は通常0.5
〜30重量%(コバルト被着酸化鉄全体における割
合)、好ましくは1〜25重量%である。
The cobalt-deposited iron oxide used in the second magnetic layer of the magnetic recording medium of the present invention is produced by a conventional cobalt-deposition method using acicular iron oxide as a nucleus. The magnetic characteristics can be adjusted to predetermined values by controlling the amount of cobalt added and the amount of Fe 2+ in the manufacturing conditions. The amount of cobalt added is usually 1 to 20% by weight (based on the raw iron oxide), preferably 2 to 15% by weight, and the amount of Fe 2+ is usually 0.5.
-30 wt% (proportion in the total cobalt-coated iron oxide), preferably 1-25 wt%.

【0013】本発明の磁気記録媒体の第2磁性層に使用
されるコバルト被着酸化鉄は、保磁力が1300Oe以
上であれば、粒径は特に限定されないが、平均長軸長が
0.1〜10μm 、平均短軸長が0.01〜0.1μm
程度が一般的であり、形状は限定されないが針状のもの
が好適に使用される。
The cobalt-adhered iron oxide used in the second magnetic layer of the magnetic recording medium of the present invention is not particularly limited in particle size as long as it has a coercive force of 1300 Oe or more, but has an average major axis length of 0.1. -10 μm, average minor axis length 0.01-0.1 μm
The degree is general, and the shape is not limited, but needle-like ones are preferably used.

【0014】第2磁性層は、上記のようなコバルト被着
酸化鉄と結合剤を主成分とする磁性塗料を、第1磁性層
上に塗布して形成されるが、第2磁性層の厚さは0.1
〜3μm が好ましい。
The second magnetic layer is formed by applying a magnetic coating material containing the above cobalt-coated iron oxide and a binder as a main component on the first magnetic layer. Sa is 0.1
-3 μm is preferred.

【0015】本発明において、磁性層の形成(塗布)方
法は、第1磁性層上と第2磁性層を同時に形成する方法
や1層ずつ順次形成する方法のいずれでもよく、1層ず
つ形成する場合は1層ごとにカレンダー処理してもよ
い。
In the present invention, the method of forming (coating) the magnetic layers may be either a method of simultaneously forming the first magnetic layer and the second magnetic layer or a method of sequentially forming one layer at a time, and forming one layer at a time. In this case, calendar processing may be performed for each layer.

【0016】本発明の磁気記録媒体の磁性層を形成する
磁性塗料は、第1、第2磁性層に上記の如きメタル粉末
又はコバルト被着酸化鉄を用い、その他の結合剤、有機
溶媒等の成分は共通のものが使用できる。
The magnetic coating material for forming the magnetic layer of the magnetic recording medium of the present invention uses the above-mentioned metal powder or cobalt-coated iron oxide for the first and second magnetic layers, and other binders, organic solvents, etc. Common components can be used.

【0017】本発明に使用される結合剤としては、ウレ
タン樹脂、特にスルホン酸基、スルホン酸金属塩基、ス
ルホベタイン基、カルボベタイン基、アミノ基、水酸
基、エポキシ基等の極性基を含有するポリウレタン樹
脂、塩化ビニル−酢酸ビニル共重合体、塩化ビニル−塩
化ビニリデン共重合体、塩化ビニル−アクリロニトリル
共重合体等の塩化ビニル系共重合体であって、特にスル
ホン酸基、スルホン酸金属塩基、アミノ基等の極性基を
含有する塩化ビニル共重合体、ブタジエン−アクリロニ
トリル共重合体、ポリアミド樹脂、ポリビニルブチラー
ル、セルロース誘導体(セルロースアセテートブチレー
ト、セルロースプロピオネート、ニトロセルロース
等)、スチレン−ブタジエン共重合体、ポリエステル樹
脂、各種の合成ゴム系、フェノール樹脂、エポキシ樹
脂、尿素樹脂、メラミン樹脂、フェノキシ樹脂、シリコ
ン樹脂、アクリル系反応樹脂、高分子量ポリエステル樹
脂とイソシアネートプレポリマーの混合物、ポリエステ
ルポリオールとポリイソシアネートの混合物、尿素ホル
ムアルデヒド樹脂、低分子量グリコール/高分子量ジオ
ール/イソシアネートの混合物、及びこれらの混合物等
が例示され、第1磁性層及び第2磁性層ともに同様のも
のが使用できる。通常、結合剤は磁性塗料中に3.0〜
10.0重量%程度配合される。
The binder used in the present invention is a urethane resin, especially a polyurethane containing a polar group such as a sulfonic acid group, a metal sulfonate group, a sulfobetaine group, a carbobetaine group, an amino group, a hydroxyl group, an epoxy group. Resins, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, and other vinyl chloride-based copolymers, particularly sulfonic acid groups, sulfonic acid metal bases, amino Chloride copolymers containing polar groups such as groups, butadiene-acrylonitrile copolymers, polyamide resins, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer Coalesced, polyester resin, various synthetic rubber, Nol resin, epoxy resin, urea resin, melamine resin, phenoxy resin, silicone resin, acrylic reaction resin, mixture of high molecular weight polyester resin and isocyanate prepolymer, mixture of polyester polyol and polyisocyanate, urea formaldehyde resin, low molecular weight glycol / Examples include high molecular weight diol / isocyanate mixtures, and mixtures thereof, and similar materials can be used for the first magnetic layer and the second magnetic layer. Usually, the binder is 3.0-
About 10.0% by weight is blended.

【0018】有機溶媒としては、シクロヘキサノン、メ
チルエチルケトン、メチルイソブチルケトン、酢酸エチ
ル、酢酸ブチル、ベンゼン、トルエン、キシレン、ジメ
チルスルホキシド、テトラヒドロフラン、ジオキサン
等、使用する結合剤樹脂を溶解するのに適した溶剤が特
に制限されることなく単独又は二種以上混合して使用さ
れる。通常、有機溶媒は磁性塗料中に20〜80重量%
程度配合される。
As the organic solvent, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, benzene, toluene, xylene, dimethyl sulfoxide, tetrahydrofuran, dioxane and the like are suitable solvents for dissolving the binder resin used. There is no particular limitation and they may be used alone or in combination of two or more. Usually, the organic solvent is 20 to 80% by weight in the magnetic paint.
The degree is mixed.

【0019】なお、磁性塗料中には、通常使用されてい
る各種添加剤、例えば分散剤、研磨剤、潤滑剤などを適
宜に添加使用してもよい。分散剤としては、レシチン、
ノニオン系界面活性剤、アニオン系界面活性剤、カチオ
ン系界面活性剤等が使用できる。研磨剤としては、α−
アルミナ、溶融アルミナ、酸化クロム(Cr2O3) 、酸化
鉄、炭化ケイ素、コランダム、ダイヤモンド等の平均粒
子径0.05〜1μm の微粉末が使用でき、通常前記し
たような結合剤100重量部に対し0.5〜100重量
部加えられる。また、潤滑剤としては、各種のポリシロ
キサン等のシリコーンオイル、グラファイト、二硫化モ
リブデン等の無機粉末、ポリエチレン、ポリテトラフル
オロエチレン等のプラスチック微粉末、高級脂肪酸、高
級アルコール、高級脂肪酸エステル、フルオロカーボン
類などが前述した結合剤100重量部に対して0.1〜
50重量部の割合で添加される。
In the magnetic coating composition, various commonly used additives such as dispersants, abrasives and lubricants may be appropriately added and used. As the dispersant, lecithin,
Nonionic surfactants, anionic surfactants, cationic surfactants and the like can be used. As an abrasive, α-
Fine powders having an average particle size of 0.05 to 1 μm, such as alumina, fused alumina, chromium oxide (Cr 2 O 3 ), iron oxide, silicon carbide, corundum, and diamond can be used, and usually 100 parts by weight of the binder as described above. 0.5 to 100 parts by weight is added. Examples of lubricants include silicone oils such as various polysiloxanes, inorganic powders such as graphite and molybdenum disulfide, fine plastic powders such as polyethylene and polytetrafluoroethylene, higher fatty acids, higher alcohols, higher fatty acid esters, and fluorocarbons. Is 0.1 to 100 parts by weight of the above-mentioned binder.
It is added in a proportion of 50 parts by weight.

【0020】本発明の磁気記録媒体に用いられる基材と
しては、合成樹脂(例えばポリエチレンテレフタレー
ト、ポリエチレンナフタレート等のポリエステル、ポリ
アミド、ポリオレフィン、セルロース系誘導体)、非磁
性の金属、ガラス、セラミック、紙等が挙げられ、その
形態は、フィルム、テープ、シート、カード、ディスク
等で使用される。
The base material used in the magnetic recording medium of the present invention includes synthetic resins (for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyamides, polyolefins, cellulose derivatives), non-magnetic metals, glass, ceramics and papers. Etc., and the form thereof is used in films, tapes, sheets, cards, disks and the like.

【0021】[0021]

【発明の効果】本発明によれば、高密度記録が可能で、
電磁変換特性と物理的特性がバランス良く向上した磁気
記録媒体が得られる。特に、本発明の磁気記録媒体は、
S/Nが向上し、摩擦係数が低く、走行性が良好でヘッ
ド目詰まりが少なく、しかもメタル粉末のみを用いた磁
気記録媒体に比べて飽和磁束密度の低下が少ない。
According to the present invention, high density recording is possible,
A magnetic recording medium having a well-balanced improvement in electromagnetic conversion characteristics and physical characteristics can be obtained. In particular, the magnetic recording medium of the present invention is
The S / N ratio is improved, the friction coefficient is low, the running property is good, the head is not clogged, and the decrease in the saturation magnetic flux density is smaller than that of the magnetic recording medium using only metal powder.

【0022】[0022]

【実施例】以下実施例にて本発明を更に説明するが、本
発明はこれらの実施例に限定されるものではない。
The present invention will be further described in the following examples, but the present invention is not limited to these examples.

【0023】実施例1〜2及び比較例1〜3 下記の成分をサンドミルにて分散し、第1磁性層用の磁
性塗料又は第2磁性層用の磁性塗料を調製した。なお、
磁性粉は、表1に示すものを用い、第1磁性層及び第2
磁性層に用いた磁性粉は表2の通りである。なお、いず
れの磁性塗料も塗布直前にコロネートL〔日本ポリウレ
タン工業 (株) 製の硬化剤〕3重量部(対磁性粉100
重量部)を加えた。 <磁性塗料成分> ・磁性粉(A〜E,表1参照) 100重量部 ・カーボンブラック(平均粒子径0.02μm ) 5重量部 ・アルミナ(平均粒子径0.3μm ) 5重量部 ・ポリウレタン樹脂 10重量部 (東洋紡績 (株) 製,UR8700) ・塩化ビニル樹脂 10重量部 (日本ゼオン (株) 製,MR110) ・ブチルステアレート 3重量部 ・ステアリン酸 1重量部 ・メチルエチルケトン 120重量部 ・トルエン 80重量部 ・シクロヘキサノン 80重量部
Examples 1 and 2 and Comparative Examples 1 to 3 The following components were dispersed in a sand mill to prepare a magnetic coating material for the first magnetic layer or a magnetic coating material for the second magnetic layer. In addition,
The magnetic powders shown in Table 1 are used, and the first magnetic layer and the second magnetic layer are used.
The magnetic powder used for the magnetic layer is shown in Table 2. Immediately before coating, 3 parts by weight of Coronate L [a curing agent manufactured by Nippon Polyurethane Industry Co., Ltd.] was applied to all magnetic coatings
Parts by weight) was added. <Magnetic paint components> 100 parts by weight of magnetic powder (A to E, see Table 1) 5 parts by weight of carbon black (average particle size 0.02 μm) 5 parts by weight of alumina (average particle size 0.3 μm) Polyurethane resin 10 parts by weight (Toyobo Co., Ltd., UR8700) ・ Vinyl chloride resin 10 parts by weight (Nippon Zeon Co., Ltd., MR110) ・ Butyl stearate 3 parts by weight ・ Stearic acid 1 part by weight ・ Methyl ethyl ketone 120 parts by weight ・ Toluene 80 parts by weight ・ Cyclohexanone 80 parts by weight

【0024】[0024]

【表1】 [Table 1]

【0025】注) Co−Fe:針状コバルト被着 FeOx (1.34≦x<1.
5)… FeOx を原料とし、コバルト量、Fe2+量を操作す
ることにより、所定の特性を得たものである。 メタル:鉄を95重量%、ニッケルを5重量%含む合金
Note) Co-Fe: Needle-like cobalt-deposited FeO x (1.34 ≦ x <1.
5) ... FeO x is used as a raw material, and predetermined properties are obtained by controlling the amount of cobalt and the amount of Fe 2+ . Metal: Alloy containing 95% by weight of iron and 5% by weight of nickel

【0026】[0026]

【表2】 [Table 2]

【0027】グラビアロールにて乾燥後の厚さが2.5
μm になるように厚さ7μm のポリエチレンテレフタレ
ート(PET)フィルム上に第1磁性層用の磁性塗料を
塗布し、長手磁場配向(8000G)した後、乾燥して
第1磁性層を形成した。次いで、第1磁性層上に乾燥後
の厚さが0.5μm になるように第2磁性層用磁性塗料
を塗布し、長手磁場配向(8000G)した後、乾燥し
て第2磁性層を形成し、更にカレンダー処理(80℃)
後、50℃で24時間エージングした。
The thickness after drying with a gravure roll is 2.5.
A magnetic coating material for the first magnetic layer was applied onto a polyethylene terephthalate (PET) film having a thickness of 7 μm so as to have a thickness of μm, and after longitudinal magnetic field orientation (8000 G), it was dried to form a first magnetic layer. Then, the magnetic coating material for the second magnetic layer is applied on the first magnetic layer so that the thickness after drying becomes 0.5 μm, and the magnetic field is oriented in the longitudinal magnetic field (8000 G), and then dried to form the second magnetic layer. And calendar processing (80 ℃)
Then, it was aged at 50 ° C. for 24 hours.

【0028】続いて、下記成分をサンドミルにて混合し
て調製したバックコート層用塗料を、フィルムの磁性層
を設けた面の反対の面に、乾燥厚み0.5μm となるよ
うに塗布し、その後、50℃で24時間エージングし
た。 <バックコート層層用塗料成分> ・カーボンブラック(平均粒子径0.02μm ) 32重量部 ・カーボンブラック(平均粒子径0.06μm ) 8重量部 ・ポリウレタン樹脂 20重量部 (日本ポリウレタン (株) 製、ニッポラン2301) ・ニトロセルロース 20重量部 (Hercules Powder CO. による粘度表示が1/2秒のもの) ・ステアリン酸 1重量部 ・メチルエチルケトン 160重量部 ・トルエン 80重量部 ・シクロヘキサノン 80重量部。
Subsequently, the backcoat layer coating material prepared by mixing the following components in a sand mill was applied to the surface of the film opposite to the surface provided with the magnetic layer so that the dry thickness was 0.5 μm, Then, it aged at 50 degreeC for 24 hours. <Backcoat layer coating material> Carbon black (average particle size 0.02 μm) 32 parts by weight Carbon black (average particle size 0.06 μm) 8 parts by weight Polyurethane resin 20 parts by weight (Nippon Polyurethane Co., Ltd.) , Nipollan 2301) -Nitrocellulose 20 parts by weight (viscosity indication by Hercules Powder CO. Is 1/2 second) -Stearic acid 1 part by weight-Methyl ethyl ketone 160 parts by weight-Toluene 80 parts by weight-Cyclohexanone 80 parts by weight.

【0029】以上のようにして、第1及び第2磁性層が
形成されたフィルムを8mm幅のテープ状に裁断し、8mm
カセットケースに装填して録画時間120分の8mmビデ
オカセットを作製した。得られた8mmビデオカセットに
ついて、以下の方法で摩擦係数、飽和磁束密度の減少率
(ΔBs)、S/N及びヘッドの目詰まりを評価した。
その結果を表3に示す。
As described above, the film on which the first and second magnetic layers were formed was cut into a tape having a width of 8 mm,
An 8 mm video cassette with a recording time of 120 minutes was manufactured by loading it in a cassette case. With respect to the obtained 8 mm video cassette, the friction coefficient, the saturation magnetic flux density decrease rate (ΔBs), the S / N ratio and the head clogging were evaluated by the following methods.
The results are shown in Table 3.

【0030】(1) 摩擦係数 (株) 協和テック製のテープ走行試験機を使用し、摩擦
体は外径5mmのVTR用ステンレス製のガイドピンを用
いて測定した。 (2) 飽和磁束密度の減少率(ΔBs) 8mmビデオカセットを60℃、90%RHの条件下に14
日間保存した後の飽和磁束密度の減少率〔ΔBs、減少
量を初期値に対する割合(%)で示す。〕を振動式磁力
計にて測定した。 (3) S/N 8mmビデオカセットを、ノイズメーターを接続した市販
の8mmVTR装置にセットし、輝度S/Nを、50%ホ
ワイト信号を記録、再生してノイズメーターで測定し
た。また、クロマS/N(AM,PM)もこれに準じて
測定した。 (4) ヘッドの目詰まり 8mmビデオカセットを120分走行させ、これを100
回繰り返し走行テストした後、磁気ヘッド及びを顕微鏡
観察してヘッドに付着した汚れを以下のように判定し
た。 ○:汚れが殆どない △:汚れがわずかにある ×:汚れが激しい なお、表1に、第1磁性層と第2磁性層の静磁気特性
(保磁力及び残留磁束密度)を併せて示すが、これは各
磁性塗料を単独でPETフィルム上に塗布し(いずれも
乾燥膜厚2μm )、長手磁場配向し、乾燥後カレンダー
処理した磁性層についてそれぞれ測定した値である。
(1) Coefficient of Friction A tape running tester manufactured by Kyowa Tech Co., Ltd. was used, and the friction body was measured using a stainless guide pin for VTR having an outer diameter of 5 mm. (2) Saturation magnetic flux density reduction rate (ΔBs) 8mm video cassette 14 at 60 ° C, 90% RH
The decrease rate of the saturation magnetic flux density after storage for a day [ΔBs, the decrease amount is shown as a ratio (%) to the initial value. ] Was measured with a vibrating magnetometer. (3) The S / N 8 mm video cassette was set in a commercially available 8 mm VTR device to which a noise meter was connected, and the luminance S / N was measured by recording and reproducing a 50% white signal and measuring with a noise meter. The chroma S / N (AM, PM) was also measured according to this. (4) Clogged head Run 8mm video cassette for 120 minutes,
After repeated running tests, the magnetic head and the microscope were observed under a microscope to determine the stains attached to the head as follows. ◯: Almost no fouling Δ: Slight fouling X: Severe fouling In addition, Table 1 also shows the static magnetic characteristics (coercive force and residual magnetic flux density) of the first magnetic layer and the second magnetic layer. This is the value measured for each magnetic layer obtained by coating each of the magnetic coatings alone on a PET film (each having a dry film thickness of 2 μm), longitudinal magnetic field orientation, and calendering after drying.

【0031】[0031]

【表3】 [Table 3]

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 基材と、該基材上に形成され、鉄を主体
とする強磁性金属粉末と結合剤とからなる第1磁性層
と、該第1磁性層上に形成され、保磁力が1300Oe
以上のコバルト被着酸化鉄と結合剤とからなる第2磁性
層とを有する磁気記録媒体。
1. A base material, a first magnetic layer formed on the base material, comprising a ferromagnetic metal powder mainly composed of iron and a binder, and a coercive force formed on the first magnetic layer. Is 1300 Oe
A magnetic recording medium comprising the above cobalt-coated iron oxide and a second magnetic layer comprising a binder.
JP17440593A 1993-07-14 1993-07-14 Magnetic recording medium Pending JPH0729158A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP17440593A JPH0729158A (en) 1993-07-14 1993-07-14 Magnetic recording medium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP17440593A JPH0729158A (en) 1993-07-14 1993-07-14 Magnetic recording medium

Publications (1)

Publication Number Publication Date
JPH0729158A true JPH0729158A (en) 1995-01-31

Family

ID=15977992

Family Applications (1)

Application Number Title Priority Date Filing Date
JP17440593A Pending JPH0729158A (en) 1993-07-14 1993-07-14 Magnetic recording medium

Country Status (1)

Country Link
JP (1) JPH0729158A (en)

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